I heard that mixing different tires on the front and rear on a xtype awd automatic can ruin the transfer case and tranny. Is this true? Any help would be appreciated. Thanks

 

This is true pretty much on any AWD application. If the tire sizes are different than mfr spec, it could cause the wheels to spin at speed differentials that are different than the transfer case is designed to handle and therefore cause excessive ware on its internals.

So, if the car comes equipped with wheels and tires that are the same on all 4 corners, all 4 wheels and tires should remain equal to each other.